Deformation insensitive thermal conductance of the designed Si metamaterial Lina Yang1 Quan Zhang2 Gengkai Hu1 Nuo Yang3

2025-05-06 0 0 593.13KB 13 页 10玖币

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Deformation insensitive thermal conductance of the designed Si

metamaterial

Lina Yang1, Quan Zhang2, Gengkai Hu1, Nuo Yang3*

1 School of Aerospace Engineering, Beijing Institute of Technology, Beijing 100081, China

2 School of Mathematical and Statistical Sciences, University of Galway, University Road,

Galway, H91 TK33, Ireland

3 School of Energy and Power Engineering, Huazhong University of Science and Technology,

Wuhan 430074, China

Email: nuo@hust.edu.cn (N. Yang)

Abstract

The thermal management have been widely focused due to broad applications. Generally,

the deformation can largely tune the thermal transport. The main challenge of flexible

electronics/ materials is to maintain thermal conductance under large deformation. This work

investigates the thermal conductance of a nano-designed Si metamaterial constructed with

curved nanobeams by molecular dynamics simulation. Interestingly, it shows that the thermal

conductance of the nano-designed Si metamaterial is insensitive under a large deformation

(strain~-41%). The new feature comes from the designed curved nanobeams which makes a

quasi-zero stiffness. Further calculations show that, when under a large deformation, the

average stress in nanobeam is ultra-small (<151 MPa) and its phonon density of states are little

changed. This work provides valuable insights on multifunction, such as both stable thermal

and mechanical properties, of nano-designed metamaterials.

Keywords: Silicon metamaterial, deformation effect, thermal conductance, stress and strain,

flexible electronics

1. Introduction

Rationally designed metamaterials by the advanced fabrication techniques[1,2] have attracted

great attention due to their new functionality, such as high strength/stiffness to weight ratio[3],

recoverability under strain[2], low thermal conductivity[4-8], damage resistance[9] and quasi-

zero-stiffness[10]. Designing nanostructured metamaterials are of great importance to achieve

unprecedent multifunction.

The thermal properties of metamaterials can be severely suppressed by designing nanoscale

structures, which benefits applications in phononics, thermoelectrics and thermal insulations

etc.[11,12] However, most of nanostructured metamaterials are designed relatively simple in

morphology, such as nanomesh[5], phononic crystal[7] and nanophononics with local

resonators[8]. Designing morphologies of nanostructures provides new degrees of freedom to

manipulate thermal properties.[13-16] For example, curved nanostructures, like kinked/bent

nanowires and nanoribbon, can cause large modulation of thermal conductivity (𝜅 ).[15,17-21]

Moreover, designing film with a wavy-structure can endow rigid film with flexibility.[22,23]

Therefore, the thermal properties of metamaterial with designed morphology needs further

investigation.

A deformation or strain is inevitable for devices in practical applications. Especially, flexible

electronics and devices involve large deformation. Therefore, it is demanded that metamaterials

possess stable thermal and mechanical properties under large deformation.[24] However, many

investigations found that the deformation has an obvious effects on 𝜅 of nanostructures.[25-31]

Only a few works reported an insensitive 𝜅 under a smaller deformation (strain <1%.).[32,33] It

is less studied that nanostructured metamaterials have insensitive κ under a larger deformation.

Whether a nanostructured metamaterial with designed morphology can have both stable

mechanical property and thermal property under deformation? Here, a metamaterial with

designed curved Si nanobeams (DCSiNBs) is studied with a large deformation (strain~-41%)

by nonequilibrium molecular dynamics (NEMD). The deformation effect on thermal

conductance (𝜎) is systematically investigated. Further, the stress and phonon density of states

(DOS) are calculated to understand the underlying mechanism.

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摘要：

DeformationinsensitivethermalconductanceofthedesignedSimetamaterialLinaYang1,QuanZhang2,GengkaiHu1,NuoYang3*1SchoolofAerospaceEngineering,BeijingInstituteofTechnology,Beijing100081,China2SchoolofMathematicalandStatisticalSciences,UniversityofGalway,UniversityRoad,Galway,H91TK33,Ireland3SchoolofEnerg...

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Deformation insensitive thermal conductance of the designed Si metamaterial Lina Yang1 Quan Zhang2 Gengkai Hu1 Nuo Yang3

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